This invention generally relates to compact fluorescent lamps and, more particularly, to a composite base member which includes a lamp ballast and electrical adapter and which is adapted to have operatively mounted thereon a single-ended fluorescent lamp of the compact type.
Preheat ballasts for fluorescent are well known and have been used for many years. In the simplest form of such ballast, when the starting voltage required for the lamp is not greater than the supply voltage, the ballast may be a simple inductor or choke which merely limits the current. Without power factor correction, such choke-type ballasts provide low power factors of about 45% to 60%. It is known to use separate capacitors with such a choke, in order to improve the power factor. Such ballast designs are generally discussed in the Westinghouse Lamp Division Lighting Handbook, revised June 1961, pages 3-32 and 3-33.
A series-connected choke and capacitor used to ballast a low pressure mercury discharge lamp are disclosed in German Pat. No. 2,155,488 dated May 31, 1972. A diode bridge plus PTC resistor plus a glow switch are used to provide ignition and reignition for the lamp.
A PTC resistor used to shunt a capacitor which serves as a part of a ballast impedance for fluorescent lamps is disclosed in U.S. Pat. No. 4,082,981, dated Apr. 4, 1978 to E. W. Morton, the present applicant.
Single-ended compact fluorescent lamps of various designs have received much attention in recent years due to the long life of such lamps and their improved efficiency of operation as compared to a conventional incandescent source. One type of such lamp is disclosed in U.S. Pat. No. 3,521,120, dated July 21, 1970 to J. M. Anderson wherein a radio-frequency power source is positioned in the base member of the lamp and is used to generate a radio frequency discharge within the lamp enevelope.
In the U.S. Pat. No. 3,815,080, dated June 4, 1974 to F. Summa is disclosed a fluorescent lamp adapter wherein a ballast transformer is positioned within a composite base member to which an elongaged fluorescent lamp is adapted to be affixed. This permits the insertion of a standard fluorescent lamp in an incandescent lamp socket fixture without modification.
In U.S. Pat. No. 3,953,761, dated April 27, l976 to T. LoGiudice is disclosed a single-ended compact fluorescent lamp wherein convoluted envelopes of varying designes are wrapped about a central core which encloses the lamp ballast.
In U.S. Pat. No. 3,899,712, dated Aug. 12, 1975 to Witting is disclosed a compact single-ended fluorescent lamp wherein the envelope is provided with a helical shape with the lamp ballast enclosed within the centrally disposed channel which is enclosed by the helical shaped envelope.